Which of the following four items are considered primary factors in natural selection? A) struggle for existence
B) gene pool
C) adaptation
D) descent with modification
E) genetic drift
F) the heritable genetic variation of individuals
G) mass extinction events
H) geological events, such as volcanic eruptions and earthquakes

Which of the following matches the organisms described with the correct domain? a. archaea--multicellular, eukaryotic organisms that do not have cell walls b. eukarya--single-celled and multicellular organisms, with a defined nucleus and a variety of nutritional sources c. bacteria--unicellular, eukaryotic organisms with cell walls that do not contain peptidoglycan d. bacteria--unicellular, eukaryotic organisms that always lack cell walls